Questions

Normal Gas welding use oxygen-acetylene.

Depending on what materials you are welding, there are some more options that might be used.

For example - MIG/TIG use Argon, MAG use an argon-something mix.

The perfect paging size varies from system to system, so there is no single best when it reaches to page size. There are several factors to consider in order to come up with a fitting page size, such as paging time, page table, and its effect on the total performance of the operating system.

Ecology is the branch of science which deals with the study of Ecosystem (relation between the Organisms and their Environment.)

If you were to produce a protein in bacterial cloning systems, you would not get the same post transcriptional and post translational modifications because the prokaryotic and eukaryotic systems work differently on the modifications.

Thus human recombinant protein genes are usually cloned in yeast cells. Also since they have a short generation time, they can be easily culture.